According to Bechtel's book, "Reptile and Amphibian Variants", an albino lacks melanin which makes the dark pigment so the eyes are red.
In leucism the chromatophores, iridophores and xanthophores which all have to do with color are not produced, so no color or pattern is seen. A leucistic turtle is pure white with dark eyes. The lighter colored snappers just have various degrees of hypomelanism or a reduction of melanin.